The present invention relates to a harrow comprising transversely with respect to the direction of travel of the harrow extending harrow teeth supporting beams, a shaft also extending transversely with respect to the direction of travel of the harrow, wobble discs secured to the shaft and cooperating with pairs of rollers connected to the beams in such a way that the beams and the harrow teeth supporting thereby are reciprocated transversely with respect to the direction of travel of the harrow by rotation of the wobble discs.
A harrow of the kind indicated above is known from U.S. Pat. No. 1,751,887. The wobble discs of this known harrow are planar circular discs secured to the corresponding shaft in such a way that the plane of each disc forms an angle with the longitudinal direction of the shaft. The beams to which the harrow teeth are secured are supported by means of frames which are slidably mounted with respect to the shaft of the discs. Each frame supports two rollers which engage opposite sides of a wobble disc. According to this prior art the rollers must be spaced apart so as to be able to accomodate the oblique disc therebetween. Accordingly, it is not possible to avoid gaps between a pair of rollers and the corresponding wobble disc and, accordingly, the beams supporting the harrow teeth will not be positively controlled.